JPS5932786A - Method of preheating raw material in arc furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a 11'' process for preheating raw materials in an arc furnace.

Conventionally, in order to improve efficiency in steelmaking using an arc furnace, two furnace bodies were used as a set, and one of the two furnace bodies was covered with a furnace cover equipped with an electrode. Melting and refining□
Then, raw Fl was charged into the other reactor body and 1! This method is known as the twin furnace method. In this case, υl gas generated in the furnace during arc melting was used as the preheating gap. However, when melting and refining stainless steel, the furnace is operated in an oxygen-blocking state as much as possible to prevent oxidation of chromium, etc., so a large amount of high-temperature exhaust gas cannot be obtained, so this exhaust gas is used as a heat source gas for preheating. It is insufficient.

This invention has been made in view of the above points, and achieves the desired temperature by blowing combustion gas of fuel into the furnace body and shaking the furnace body. It is an object of the present invention to provide a method for preheating raw materials in an arc furnace that can utilize + heat amount and perform preheating with less uneven heat.

An embodiment of the present invention will be explained with reference to the drawings.

In the figure, IIL and 11. + is the furnace body of the arc furnace, both of which have a trunnion shaft 2, a motor 3, and a reducer 4.
It is tilted forward and backward via a row of teeth ILC by a drive device 5 consisting of 4:q, and 6 is a tapping (through).
a to 7 (- indicates the eight burners (collectively referred to as bars 7) installed on the (1111) wall of each fj body, and the Kubushi-yaki gas injection formed by the bar tile part [-J8 indicates the molten steel Uin (
It is provided on the side wall above the sill line (9) and opens toward the center of the bottom. Burner 7 uses heavy oil, molten oil,
It is connected to a fuel supply source such as LNG via flexible piping. There are still 10 pieces (11L111) on both sides of the foundation, and the rails laid on the pitch 11, 12
is a trolley mounted on these rails 10, 10 so as to be freely movable, and is equipped with a self-propelled device similar to the overhead crane. The J3j shingles 13 adhering to the furnace body 1a and the electric wires 11 and 14 penetrating the furnace lid are taken out via a sieve device A similar to the ordinary steelmaking arc tl-1 on the platform ff111.12. Kicked +1. The furnace lid 11ii15 and the electrode support arm 16 are respectively accessible. On the other hand, the furnace body 11)
Ji73 curved exhaust gas duct 1 is attached to the surface 17.
8 is fixed, and the end of this duct is coaxial with the trunnion shaft 2 of the furnace body, and the rotary cylinder 20 of the rotary joint 19 that serves
It is removably connected by a clamp mechanism (not shown).

Rotating silk: The hand 19 rotates f on the cylindrical body 21 fixed to the foundation.
20 is rotatably fitted, and has a built-in damper 22. A duct 23 is connected to the cylindrical body 21, and is connected to a scrap breaker heater (not shown).

With the apparatus of the above configuration, fl! of stainless steel is produced! 4! The furnace for preheating the steel and raw materials is located in the furnace body la as shown in the diagram.
) When melting and scouring the raw material by energizing the electrode 14, charge the raw material 24 into the furnace body 11) and close the lid 1.
7 by a crane (not shown) or the like.

The end of the exhaust gas duct 18 is connected to the moving joint 19 on the side of the furnace body, and the damper 22 is opened. Next, the drive unit 5 drives the body 11. Tilt + as shown in Fig. 4)・- 7) With 1 in the backward tilted position, supply fuel to burner 7 and blow the combustion gas. The raw material 24 is preheated by blowing higher temperature combustion gas into the car 11+.

The combustion gas flowing through the raw material 24 is +11 gas duct 1
8. It is led to the scrap breech heater through the rotation joint 19 and duct 23, and is used to preheat the dope for the next charging charged into the scrap breech, and is then discharged into the atmosphere through the aging device. . The furnace body is tilted backwards for a predetermined period of time (for example, 1
0 minutes) After blowing the combustion gas, the drive device 5
Then, the furnace body 11J is tilted in the opposite direction to a state of 6iJ ft/j where the burners 7t) and 7C are on the lower side as shown by chain lines in FIG. 4, and combustion gas is blown in the same way. The furnace body remains tilted forward for a predetermined period of time (for example, 1 hour).
After injecting combustion gas (for 0 minutes), return to the +lf and backward tilted state, and repeat this as necessary. Since the furnace body 1b is oscillated between the backward tilted state and the forward tilted state, the original material 124 of the bulk alloys and scraps inside the furnace body is moved 1~, the raw material The flow path of the combustion gas in the furnace changes, and the raw material is heated almost uniformly.The raw material 24 is primary heated to about 200°C by the scrap breech heater and charged into the 01 body 11). 1 +
At the time of completion of steel making 1 being carried out at i, the temperature of burner 7 is set so that the temperature is 800 degrees (1111 degrees) at the time of completion of steel making 1 being carried out at i.
, Preheat the hanging. After preheating is completed, return the gas body 11 to its initial upright position and connect the p1 gas duct 18 to the rotation joint 19.
After separating it from the furnace body 1a, it is removed from the furnace body 11)-1 together with 1γ3-17 using a crane or the like, and then the furnace lid 13 and the electrode 14 are moved from the furnace body 1a by the trolley 12 (. The preheated raw material 24 is melted and refined by arc heating.Meanwhile, a new raw material is charged into one of the furnaces that have been tapped, and the same raw materials as above are charged in this furnace body. Preheating is carried out.Furthermore, the combustion of fuel in each bar 721 to 7 (l) of the L body during the heating of the raw material may be performed by temporarily stopping combustion as appropriate for adjusting the raw material temperature or for other reasons. good.

The present invention is not limited to the illustrated embodiment, and the number k and number 7 may be other than three.

In particular, the bar plate 72 installed on the length 1 of the bar plate 6
If there is only one ↓, the furnace body is tilted backwards p(: and 11
``J-17 may be used to oscillate between the standing state and
Twisting of the raw material [heating by blowing gas] is carried out in the state shown in Fig. 4,
If the furnace body is held upright or tilted forward for a very short time, the raw material will be heated as if by a burner installed at the bottom of the furnace body, and the rocking of the furnace body will have a uniform heating effect. Combined with this, the heat IA of the combustion gas is sufficiently transferred to the raw material, resulting in high heating efficiency. In addition, in the embodiment described in (-), the combustion gas from the burner 7 installed in the furnace body is blown directly into the furnace body, which has the advantage of good thermal efficiency. A combustion device burns low-cost fuel such as pulverized coal and tar, and the combustion gas shown in (1) is guided to the combustion gas injection 1-1, which is drilled through the furnace wall of the furnace body, through NF flexible piping, and the combustion gas is introduced into the furnace interior. You may also inject it into the

Further, the furnace body may be rocked by a rocker type tilting device or the like.

The following is a case in which this invention is applied to a twin furnace type stainless steel refining arc.
It can be applied to preheating raw materials in arc furnaces for melting and refining various metals other than stainless steel and non-ferrous metals).

As explained above, this light 1 step is IJi
! Since the raw material is preheated by blowing combustion gas into the furnace body charged with i-1, the amount of heat for preheating can be freely selected, and the raw material can be preheated to a desired temperature at a desired time. In addition, since the furnace body charged with raw materials is oscillated, the raw materials are less likely to be locally overheated or insufficiently heated.
The raw materials are heated almost evenly.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of the apparatus used for carrying out the method of the present invention, FIG. Figure 4 is a longitudinal sectional view of the furnace body during operation. 12... 1 furnace, 11]... Furnace body, 2... Trunnion 11, 5... Drive device, 7 a~7 (2...
Burner, 8... Combustion gas blowing] -1, 9... Molten steel line, 17... Lid, 18... Exhaust gas duct, 24...
··material. Applicant Daido Steel Co., Ltd. 1711 persons Masao Inui No. 2, No. 3

Claims (1)

[Claims] A combustion gas inlet is provided on the side wall of the arc furnace body toward the molten metal line, and after charging the raw material into the furnace body, a lid equipped with a Jul gas duct is attached to the furnace body, 2. A method for preheating raw material in an arc furnace, characterized in that combustion gas is blown into the furnace body through the combustion gas inlet to heat the raw material, and at the same time, the body of the furnace body is oscillated.